Zooming in and out: Scale dependence of extrinsic and intrinsic factors affecting salt marsh erosion
Zooming in and out: Scale dependence of extrinsic and intrinsic factors affecting salt marsh erosion
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DOI：
10.1002/2016jf004193
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发表时间：
2017-07
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影响因子：
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通讯作者：
Heng Wang;D. Wal;Xiangyu Li;J. Belzen;P. Herman;Zhan Hu;Zhenpeng Ge;Li-Quan Zhang;T. Bouma
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文献类型：
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作者：
Heng Wang;D. Wal;Xiangyu Li;J. Belzen;P. Herman;Zhan Hu;Zhenpeng Ge;Li-Quan Zhang;T. Bouma
盐沼是有价值的生态系统，提供重要的生态系统服务。鉴于气候变化和海岸挤压导致的全球范围的沼泽损失，迫切需要确定影响盐沼边缘侵蚀的关键外部因素（风暴露和前海岸形态）和内在因素（土壤和植被性质）。在这项研究中，我们使用在荷兰Westerschelde河口四个盐沼地点拍摄的时间序列航空照片，量化了悬崖侧向退缩（即盐沼高原的侵蚀边缘）的速率。此外，我们还利用波浪槽对这四个沼泽边缘沉积物岩心的可蚀性进行了实验量化。结果表明：(1)在大尺度上，风暴露和崖前先锋植被的存在是控制崖退率的关键因素；（ii）在中等尺度上，前滩形态与悬崖退缩部分相关；(3)在局地尺度上，沼泽边缘沉积物本身的可蚀性对悬崖退缩速率起着重要的决定作用；（iv）在中生态尺度上，悬崖的可蚀性由土壤性质和地下根系生物量决定。因此，外在因素和内在因素都决定了盐沼的命运，但在不同的尺度上。我们的研究强调了理解驱动盐沼景观演变的因素的尺度依赖性的重要性。
Salt marshes are valuable ecosystems that provide important ecosystem services. Given the global scale of marsh loss due to climate change and coastal squeeze, there is a pressing need to identify the critical extrinsic (wind exposure and foreshore morphology) and intrinsic factors (soil and vegetation properties) affecting the erosion of salt marsh edges. In this study, we quantified rates of cliff lateral retreat (i.e., the eroding edge of a salt marsh plateau) using a time series of aerial photographs taken over four salt marsh sites in the Westerschelde estuary, the Netherlands. In addition, we experimentally quantified the erodibility of sediment cores collected from the marsh edge of these four marshes using wave tanks. Our results revealed the following: (i) at the large scale, wind exposure and the presence of pioneer vegetation in front of the cliff were the key factors governing cliff retreat rates; (ii) at the intermediate scale, foreshore morphology was partially related to cliff retreat; (iii) at the local scale, the erodibility of the sediment itself at the marsh edge played a large role in determining the cliff retreat rate; and (iv) at the mesocosm scale, cliff erodibility was determined by soil properties and belowground root biomass. Thus, both extrinsic and intrinsic factors determined the fate of the salt marsh but at different scales. Our study highlights the importance of understanding the scale dependence of the factors driving the evolution of salt marsh landscapes.